If a disaster such as a flood strikes a library, valuable library volumes that have taken years to collect can be completely destroyed by water. Water emergencies are invariably more damaging to books than any other type of disaster, including fire. Unfortunately, water emergencies happen rather frequently in libraries. Water emergencies are caused by a variety of unforeseen problems such as roof leaks, backed up sewer lines, burst pipes, accidental sprinkler system discharge, storm flooding, the result of putting out a fire, among other unforeseen events that often strike without warning. For libraries to salvage books and like materials (hereinafter "books"), that have become water soaked, the standard practice is to place the dripping wet books in a container, freeze the books and then dry them in some manner. After the books have been frozen, the preferred method of drying is vacuum freeze drying. Vacuum freeze drying can be accomplished while the books are in a suitable box that permits air to circulate through the box walls. It has been found that if the books have sustained no damage other than wetting such process can substantially completely restore the books to their original condition, assuming that the initial freezing is undertaken quickly, before fungal growth and decomposition has occurred (usually within 48 to 72 hours).
A problem however arises in that transporting the books to a freeze dry facility requires a voluminous number of carriers, and in order to be prepared to respond quickly to a disaster, it is desirable for libraries to store at least enough carriers to last for the first 24 hours or so until more can be brought in. Generally two types of carries are in use, milk crates or corrugated, cardboard boxes, because both types allow for quick freezing of contents and allow adequate air circulation to facilitate the vacuum freeze drying process.
Unfortunately, an immense storage problem is created for the libraries and vacuum freeze drying facilities that choose to stock milk crates. Apart from the storage problem, however, the commercial milk crate is an ideal carrier because it has bottom and sides molded in a fretwork structure to provide large open spaces, it requires no top for stacking, it is a size that can be handled easily when filled with heavy, wet books, it (the commercial variety) is made of polyethylene so that it has good impact strength at very cold temperatures. Functionally, the milk crates permit rapid drainage, rapid freezing and rapid vacuum freeze drying. From the standpoint of library security, the fact that the milk crate has no top is a slight disadvantage. Nonetheless, milk crates set the standard for this purpose in the industry.
The problem with cardboard boxes is that they soak up water, cannot be reused and at times cannot last even one cycle particularly when the books are very wet. Yet, the California library system stockpiles several thousand cardboard boxes, because they are easily stored, and it is better to have a quantity of cardboard boxes on hand than to have nothing at all in an emergency.
A slight improvement over the plain corrugated box might be boxes that are wax coated to extend their useful lives. Such treatment, however, extends the life of these cartons to maybe two to three uses at best, nowhere near the life span of plastic boxes. Furthermore, the wax coating can produce its own problems. One problem, if the interior surfaces of the cartons are waxed, is that cracking of the wax can cause wax deposits on the covers of the books, particularly books with linen or other coarsely woven surfaces; such a wax deposit could irreparably damage rare books or at least necessitate costly rebinding. An additional problem with wax coated corrugated board is that airflow, necessary to the vacuum freeze drying process, is inhibited by a heavy wax coating. This problem of insufficient airflow can be solved by the strategic placement of enough holes in the container to permit good air circulation, but not so many or such large holes that the container looses its strength. Some wax coated corrugated food boxes may meet these requirements. However, even with the wax coating, migration of water through the wax to the cardboard occurs at times, particularly at folds and at cut edges, where water can be wicked into the interior flutes of the corrugated board. More expensive, more thorough interior and exterior coatings can mitigate this problem. Nevertheless, the life span of coated paperboard containers is still much less than that of plastic boxes. Finally, maintaining the shelf life of wax coated boxes during long term storage can be difficult if the humidity is high (causing moisture absorption) or if the temperature is warm (causing waxed surfaces to stick together).
Another way that library salvage workers have tried to make corrugated boxes last longer is to place large plastic bags inside the boxes before loading the wet books. Then after the books are frozen, the bags are removed for the vacuum freeze drying operation. This is a very labor intensive solution.